Electrical programmed fuses (“eFuses”) are widely used in semiconductor integrated circuits (ICs). An eFuse has two states, blown and unblown. Generally, an unprogrammed eFuse is in the unblown state while a programmed eFuse is in the blown state. A sensing circuit is employed to sense the state of the eFuse.
In conventional eFuses, a reference resistor is used. The reference resistor has a resistance which is equal to the mid-point between the resistance of a blown fuse and that of an unblown fuse. The sense circuit senses whether the fuse resistance is greater or smaller than resistance of the resistor.
However, the use of a resistor is sensitive to process and temperature variations. For example, the value of the resistor may vary due to process variations as well as temperature variations, resulting in a narrow sensing window. Furthermore, conventional fuse circuits have large power consumption as well as slow sensing speed.
From the forgoing discussion, it is desirable to provide a fuse circuit which has a large sensing window and high sensing speed with low power consumption.